Circuits used heretofore for controlling the closure time interval of an electronic switch in the circuit of the primary winding of an ignition transformer usually operate on an extrapolated basis, which is to say that the engine rotation angle during which the switch is closed is determined by speed information that was determined at some preceding time. During dynamic transitions (acceleration or slowing down of engine speed) the errors are so large at low speeds even for relatively small acceleration values that the ignition can malfunction. In the case of deceleration the switch closure interval can be too great, so that the final transistor located in the primary circuit of the ignition transformer and even the ignition transformer itself can be too heavily loaded. If the speed is zero, a supplementary circuit is necessary for shutting off the quiescent current, since the current through the ignition transformer would produce an excessive current drain if prolonged.